Synthesis and reactivity of η5-tetramethylcyclopentadienyl-propenyl rhenium complexes: Molecular structure of [(η5:η2-C5Me4CH2CH{double bond, long}CH2)Re(CO)2]

Article abstract of DOI:10.1016/j.jorganchem.2009.10.042

The fulvene complexes [(η⁶-C₅Me₄CH₂)Re(CO)₂(R)] (1a, R{double bond, long}I; 1b, R{double bond, long}C₆F₅) react at the exocyclic methylene carbon with a vinylmagnesium bromide solution to produce the anionic species [(η⁵-C₅Me₄CH₂CH{double bond, long}CH₂)Re(CO)₂(R)]^-. Protonation with HCl at 0 °C produces the hydride complexes [trans-(η⁵-C₅Me₄CH₂CH{double bond, long}CH₂)Re(CO)₂(R)(H)] (2a, R{double bond, long}I; 2b, R{double bond, long}C₆F₅). Thermolysis of an hexane solution of the iodo-hydride (2a) under a CO atmosphere yields the complex [(η⁵-C₅Me₄CH₂CH{double bond, long}CH₂)Re(CO)₃] (3) and [Re(CO)₅I] as by-product. Thermolysis of 2b produced three new products, mainly the chelated complex [(η⁵:η²-C₅Me₄CH₂CH{double bond, long}CH₂)Re(CO)₂] (4) and complex 3, with a non-coordinated olefin group, in moderated yield, and traces of [Re(CO)₅(C₆F₅)]. Thermolysis of an hexane solution of 2 in presence of an excess of PMe₃, afforded the phosphine derivative [(η⁵-C₅Me₄CH₂CH{double bond, long}CH₂)Re(CO)₂(PMe₃)] (5). All the complexes were characterized by IR, ¹H, ¹³C and ³¹P NMR spectroscopies and mass spectrometry. The molecular structure of 4 has also been determined. The molecule exhibits a formal three-legged piano-stool structure, with two CO groups, and the third position corresponding to the η²-coordination of the propenyl side arm of the η⁵-C₅Me₄ ring.

Full text of DOI:10.1016/j.jorganchem.2009.10.042

Journal of Organometallic Chemistry 695 (2010) 346–351
Contents lists available at ScienceDirect
Journal of Organometallic Chemistry
journal homepage: www.elsevier.com/locate/jorganchem
Synthesis and reactivity of
g
5-tetramethylcyclopentadienyl-propenyl rhenium
complexes: Molecular structure of [(g5 2-C5Me4CH2CH@CH2)Re(CO)2]
:g
a
b
c
d
Fernando Godoy a, , Alejandra Gómez , Gloria Cárdenas-Jirón , A. Hugo Klahn , Fernando J. Lahoz
*
a Departamento de Química de los Materiales, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Santiago, Chile
b Departamento de Ciencias del Ambiente, Facultad de Química y Biología, Universidad de Santiago de Chile, Casilla 40, Santiago, Chile
c Instituto de Química, Pontificia Universidad Católica de Valparaíso, Casilla 4059, Valparaíso, Chile
d Departamento de Química Inorgánica, Instituto de Ciencia de Materiales de Aragón, Universidad de Zaragoza-CSIC, 50009 Zaragoza, Spain
a r t i c l e i n f o
a b s t r a c t
Article history:
Received 6 October 2009
Received in revised form 24 October 2009
Accepted 26 October 2009
Available online 30 October 2009
The fulvene complexes [(
g
6-C5Me4CH2)Re(CO)2(R)] (1a, R@I; 1b, R@C6F5) react at the exocyclic methylene
carbon with
C5Me4CH2CH@CH2)Re(CO)2(R)]À. Protonation with HCl at 0 °C produces the hydride complexes [trans-
5-C5Me4CH2CH@CH2)Re(CO)2(R)(H)] (2a, R@I; 2b, R@C6F5). Thermolysis of an hexane solution of the
iodo-hydride (2a) under a CO atmosphere yields the complex [(
5-C5Me4CH2CH@CH2)Re(CO)3] (3) and
[Re(CO)5I] as by-product. Thermolysis of 2b produced three new products, mainly the chelated complex
[(g5 2-C5Me4CH2CH@CH2)Re(CO)2] (4) and complex 3, with a non-coordinated olefin group, in moder-
ated yield, and traces of [Re(CO)5(C6F5)]. Thermolysis of an hexane solution of 2 in presence of an excess
a
vinylmagnesium bromide solution to produce the anionic species [(g5
-
(
g
g
Keywords:
:
g
Rhenium complexes
Hemilabile ligand
Reductive elimination
Crystal structure
of PMe3, afforded the phosphine derivative [(g
5-C5Me4CH2CH@CH2)Re(CO)2(PMe3)] (5). All the complexes
were characterized by IR, 1H, 13C and 31P NMR spectroscopies and mass spectrometry. The molecular
structure of 4 has also been determined. The molecule exhibits a formal three-legged piano-stool struc-
ture, with two CO groups, and the third position corresponding to the
g
2-coordination of the propenyl side
arm of the
g
5-C5Me4 ring.
Ó 2009 Elsevier B.V. All rights reserved.
1. Introduction
in the homogenous catalytic polymerization of ethylene and
propene [8], while Mountford and co-workers [9] synthesized
tetramethylcyclopentadienyl titanium and zirconium derivatives
with a butenyl pendant side chain. On the other hand, few half-
sandwich compounds of this type are known for group 7 metals,
for instance, Gable and Brown [10] reported the synthesis of the
Organometallic complexes containing the cyclopentadienyl and
tetramethylcyclopentadienyl functionalized ligands (C5H4R and
C5Me4R) have become of great importance because of their capac-
ity for binding to hard and soft metal centers in a hemilabile man-
ner, giving unique chemical and physical properties to the
complex. The fragment tethered to the C5H4 or C5Me4 ligands
may included phosphines [1], amines [2], ethers [3], and sulfide
[4] groups, which have been widely studied. By choosing appropri-
ate systems and conditions the intramolecular stabilization of elec-
[(g
5-C5Me4CH2CH2CH@CH2)Re(CO)3] complex which was used as
5-C5Me4-
precursor to produce the Re(VII) epoxide complex [(
g
CH2CH2CHCH2O)Re(O)3]. Almost simultaneously, our group
reported the same tetramethylcyclopentadienyl-(3-butenyl) com-
plex using an alternative route which involves the use of the ful-
tron-deficient centers can be observed in
a
reversible or
vene complex [(
We also have reported that, the fulvene complexes [(g
g
6-C5Me4CH2)Re(CO)2(I)] as starting material.
irreversible way. For this reason, these types of compounds have
found significant applications in catalysis (olefin polymerization
[1–4], hydrogenation of ketones [5], alcohol oxidation [6], etc.)
and in the construction of molecular materials, however, from
the large amount of these ligand reported in literature, those con-
taining alkene pendant side chains are far less abundant [7]. For in-
stance, Erker et al. have reported the formation of sandwich and
half-sandwich titanium and zirconium complexes with allyl
substituted cyclopentadienyl groups, which have resulted active
6-C5Me4-
CH2)Re(CO)2(R)] (R@I, C6F5) react with allylmagnesium chloride,
2-thienyllithium and potassium diphenylphosphide to yield the
anionic species [(g
5-C5Me4CH2L)Re(R)(CO)2]À (L@CH2CH@CH2; 2-
C4H3S; PPh2). Protonation with HCl afforded the trans hydride
complexes, which under thermolysis conditions (hexane solution
under an N2 atmosphere at 40 °C) yielded the compounds
[(g5 x-C5Me4CH2L)Re(CO)2] (x = 2 and 1, respectively) [11,12].
:g
We also demonstrate that under UV irradiation of [(g5
-
-
C5Me4CH2CH2CH@CH2)Re(CO)3] the chelated complex [(g5
:
g2
C5Me4CH2CH2CH@CH2)Re(CO)2] is formed in moderate yield,
* Corresponding author. Tel.: +56 02 7181034.
species that surprisingly do not react with CO even at 1100 psi.
E-mail address: fernando.godoy@usach.cl (F. Godoy).
0022-328X/$ - see front matter Ó 2009 Elsevier B.V. All rights reserved.
doi:10.1016/j.jorganchem.2009.10.042

F. Godoy et al. / Journal of Organometallic Chemistry 695 (2010) 346–351
347
With the aim of getting a more deep insight into the formation
of this type of rhenium compounds, in this work, we describe the
thermal reactions of the hydride complexes [trans-(g5
2.2. Thermal reactions of hydride complexes
5-C5Me4CH2CH@CH2)Re(CO)2(R)(H)]
-
Hydride complexes [trans-(g
C5Me4CH2CH@CH2)Re(CO)2(R)(H)] (R@I, C6F5) with CO and PMe3.
The organometallic products were isolated and characterized by
spectroscopic techniques. In addition, the reductive elimination
(2a–b) in hexane solution under a CO atmosphere, at 45 °C undergo
reductive elimination reactions of HI and C6F5H, respectively. How-
ever, the observed organometallic product depends on the nature
of the R group coordinated to the rhenium atom (Scheme 2).
The iodo-hydride complex 2a in presence of CO produced the
of HI and C6F5H from [trans-(g
5-C5Me4CH2CH@CH2)Re(CO)2(R)(H)]
to produce complexes with a non-coordinated and coordinated
propenyl side arm is also described.
tricarbonyl complex [(g
5-C5Me4CH2CH@CH2)Re(CO)3] (3) which
was isolated as an analytically pure white solid in low yield
(26%) and [Re(CO)5I] as by-product. The latter was characterized
by IR spectroscopy and MS. The IR data was identical to those
reported for this compound by Schmidt et al. [17]. Complex 3,
showed two CO absorption bands at 2014 and 1924 cmÀ1, almost
identical to those reported for the related pentamethyl and tetra-
methylcyclopentadienyl functionalized tricarbonyl complexes
[11]. The 1H NMR spectrum of 3 shows two singlets at about
2 ppm, attributed to methyl groups of the cyclopentadienyl li-
gand, and a signal at d 3.17 assigned to the methylenic protons.
The olefinic protons were observed as three signals in the region
4.9–5.8 ppm. The chemical shifts are in good agreement with
2. Results and discussion
2.1. Synthesis of the hydride complexes
The fulvene complexes [(g
6-C5Me4CH2)Re(CO)2(R)] (1a, R@I; 1b,
R@C6F5) were prepared by methods described in the literature
[13,14]. Addition of vinylmagnesium bromide to THF solutions of
1a–b yield the anionic complexes [(g
5-C5Me4CH2CH@CH2)-
Re(CO)2(R)]À (Scheme 1). These anionic species were not isolated
due to their extreme air sensitivity, and they were characterized
those reported for the complexes [(
[(g5 5-C5H4SiMe2C5H4CH2CH@CH2)ZrCl2] [8], [TiCl2{
(SiMe2CH@CH2)}2] [18], and [(
g
5-C5H4CH2CH@CH2)TiCl3],
5-C5Me4-
5-C5Me4CH2CH2CH@CH2)Re(CO)3]
only by IR spectroscopy. Two absorption
served at 1875 and 1728 cmÀ1, comparable to those reported for
analogous rhenium anions [11,15]. Further reaction of [(g5
C5Me4CH2CH@CH2)Re(CO)2(R)]À with HCl at 0 °C gave the hydride
complexes [trans-(
5-C5Me4CH2CH@CH2)Re(CO)2(R)(H)] (2a–b)
m(CO) bands were ob-
:g
g
g
-
[10]. The 13C NMR showed, in addition to the carbons of the
C5Me4 fragment, two singlets at d: 116.0 and 137.0 attributed
to alkenyl group, and a singlet for the CO groups at d 198.2. Iden-
g
(Scheme 1). After work up the hydride complexes were isolated
as pale brown solids which were soluble in most organic solvents.
The extreme air sensitivity of the solids precluded satisfactory ele-
mental analyses. These compounds showed CO absorption bands at
2022 (v) and 1960 (vs) cmÀ1 in hexane solution, with the signal at
lower wavenumber much more intense. On the basis of the relative
intensity pattern, as well as the similarities between the IR frequen-
cies of these complexes and those of other dicarbonyl derivatives
with a four-legged piano-stool type of structure [16], we assigned
the two CO ligands in a diagonal or trans orientation in the com-
plexes 2a–b.
tical values were found for [(g
5-C5Me4CH2CH2CH@CH2)Re(CO)3]
[11]. The mass spectrum of 3 exhibits a typical fragmentation
pattern for rhenium complexes: 432 [M+], 404 [M+ÀCO], 391
[M+ÀCH2CH@CH2] and 374 [M+À2COÀ2H].
The HI formed in the thermolysis was extracted with water
(25 mL) and the pH was determined potentiometrically giving a
value of 1.68, indicating the presence of a strong acid; addition
of AgNO3 caused the quantitative precipitation of AgI.
In the thermolysis of 2b under a CO atmosphere three car-
bonyl complexes were observed by IR spectroscopy. The reaction
mixture was chromatographed on neutral alumina and the first
fraction eluted with hexane confirmed the presence of hexaflu-
orobenzene (by GC–MS). The second fraction, [Re(CO)5(C6F5)],
was isolated in low yield and characterized by IR spectroscopy
and MS [19]. The third fraction (eluted with hexane) afforded
the neutral species 3 in a 26% yield, while the chelated complex
The 1H NMR spectrum of 2a–b in benzene-d6 showed at low fre-
quency one singlet (d: À8.95 and 9.12, respectively) for the hydride
proton; this chemical shift is almost identical to those reported for
the closely related complexes [trans-(
(ArylF = C6F5, 2,3,5,6-C6HF4) [15] and [trans-(
g
5-C5Me5)Re(ArylF)(CO)2(H)]
5-C5Me4CH2P-
g
Ph2)Re(C6F5)(CO)2(H)] [12]. The presence of the (propenyl)-tetra-
methylcyclopentadienyl ligand (C5Me4CH2CH@CH2) in complex
2a–b, were established by 1H NMR spectroscopy. Partial transfor-
mation of the hydrides complexes 2a–b in solutions of d6-C6D6,
were observed by 1H NMR and IR spectroscopy, the products were
[(g5 2-C5Me4CH2CH@CH2)Re(CO)2] (4) was obtained with suc-
:g
cessive elution with hexane and isolated as a white microcrystal-
line solid in good yield (43%). The latter was soluble in most
common organic solvents, air stable, and did not decompose
after several months stored under nitrogen. The IR spectra of 4
show two CO absorption bands at 1962 and 1891 cmÀ1 described
in experimental which are similar to those reported for the eth-
characterized as [(
C5Me4CH2CH@CH2)Re(CO)2] (4) (vide infra).
Both IR and NMR parameters are similar to those found in the
analogous iodo and fluoroaryl rhenium complexes [trans-(g5
g : -
5-C5Me4CH2CH@CH2)Re(CO)3] (3) and [(g5 g2
ylene complex [(
1894 cmÀ1
in hexane) [20] and for the butenyl derivative
[(g5 2-C5Me4CH2CH2-CH@CH2)Re(CO)2] [11]. The frequency
g g m(CO) 1964 and
5-C5Me5)Re(CO)2( 2-C2H4)] (
-
,
C5Me4CH2L)Re(CO)2(R)(H)] (L@CH2CH@CH2, PPh2; R@I, C6F5)
[11,12].
:g
Scheme 1.

348
F. Godoy et al. / Journal of Organometallic Chemistry 695 (2010) 346–351
Scheme 2.
shift of the
m
(CO) bands of 4 compared to 3 suggests a stronger
tical to those reported for the analogous species [(g5 g2
: -
d–p back-bonding between rhenium and the alkene ligand. Coor-
dination of the olefin group to the rhenium fragment was con-
firmed by 1H NMR spectroscopy from the presence of three
new sets of resonances shifted to high field, which are similar
to that reported for the spectroscopy data reported for butenyl
C5Me4CH2CH2CH@CH2)Re(CO)2], fact that led us to think that both
chelated compounds have similar electron density, the effect of the
different side carbon chain apparently plays a fundamental role in
the dissociation process of the alkene group for complex 4.
Thermolysis of the hydrido complexes 2a–b, in presence of an
derivative [(g5
:g
2-C5Me4CH2CH2CH@CH2)Re(CO)2] [11]. The 13C
excess of PMe3, afforded the unchelated complex [(g5
-
NMR spectrum of 4 showed two singlets at d 31.3 and 58.3
C5Me4CH2CH@CH2)Re(CO)2(PMe3)] (5) in good yield when
starting from iodo-hydride complex 2a, but a 5:2 mixture of
complexes 4 and 5, were obtained on the thermolysis of [trans-
attributed to CH2 and CH, respectively, of the coordinated
ACH@CH2 fragment. This assignment was confirmed by 1H–13
C
HSQC NMR and by comparison with analogous complexes [11].
The high field shift of these resonances compared to those found
for the uncoordinated olefin in 3 (d 116.0 and 137.0) can be ex-
plained in terms of the Dewar–Chatt–Duncanson model, which
implies a change in the hybridization of the alkene carbon from
sp2, in the uncoordinated fragment, to a sp3-like carbon in com-
plex 4 [21]. Further evidence obtained from the 13C NMR spec-
trum are the two distinct resonances for the CO groups
observed at about d: 207, due to the unsymmetrical nature of
the side chain coordinated to the metal center. This result is in
(g
5-C5Me4CH2CH@CH2)Re(CO)2(C6F5)(H)] (2b). The trimethyl-
phosphine complex 5, was isolated as a light yellow oil after work
up. The IR and 31P NMR data of 5 are in a good agreement with
those reported for analogous rhenium complexes [(g5
-
C5Me4CH2L)Re(CO)2(PMe3)] (L@ CH2CH@CH2, 2-C4H3S, PPh2)
[11,13]. The 1H and 13C NMR data are consistent with the pro-
posed structure and clearly showed the uncoordination of the
2-propenyl side chain.
2.3. Crystal structure of complex 4
a good agreement with that reported for the complex [(g5 g2
- -
C5Me4CH2CH2CH@CH2)Re(CO)2] [11], and in addition the mass
spectrum and elemental analysis are in good agreement for the
proposed structure.
The molecular structure of complex 4 is shown in Fig. 1 and the
most relevant bond distances and angles are collected in Table 1.
This mononuclear metal complex exhibits a typical three-legged
With the aim of exploring the hemilabile character of the prope-
nyl group coordinated to the rhenium center in complex 4, we
treated it with CO (500 psi). After 3 h the IR and 1H NMR spectra
showed the presence of the tricarbonyl derivative 3 (Scheme 3).
This result highly contrasts with that found for the complex
[(g5 2-C5Me4CH2CH2CH@CH2)Re(CO)2] which even at high CO
:g
pressure (2000 psi) remained intact.
Interestingly, the process is reversible under UV irradiation
(hexane solution, k = 300 nm, room temperature). Although the
spectroscopic data (IR and 13C NMR) for complex 4 are almost iden-
Scheme 3.
Fig. 1. Molecular drawing of complex 4 with atomic numbering scheme.

F. Godoy et al. / Journal of Organometallic Chemistry 695 (2010) 346–351
349
Table 1
summarized in Scheme 3, photodissociation of one CO ligand
yields the chelated complex [(g5 2-C5Me4CH2CH@CH2)Re(CO)2]
containing an intramolecularly coordinated propenyl fragment,
the latter species reacts with CO to afforded (
CH2)Re(CO)3 in a reversible way.
Selected bond lengths (Å), and angles (°) for [(g5
:
g
2-C5Me4CH2CH@CH2)Re(CO)2] (4).
:g
Re–C(1)
Re–C(2)
Re–C(3)
Re–C(4)
2.295(4)
2.316(4)
2.312(4)
2.259(4)
2.233(4)
1.543(6)
1.543(6)
1.395(7)
105.95(12)
125.90(13)
132.38(13)
100.8(2)
100.1(2)
85.96(16)
Re–Ga
1.9327(18)
Re–Mb
2.137(3)
2.244(4)
2.252(4)
1.905(4)
1.913(4)
1.166(5)
1.161(5)
109.4(3)
124.2(4)
120.4(4)
101.0(3)
119.6(4)
g
5-C5Me4CH2CH@
Re–C(11)
Re–C(12)
Re–C(13)
Re–C(14)
C(13)–O(1)
C(14)–O(2)
C(1)–C(5)–C(4)
C(1)–C(5)–C(10)
C(4)–C(5)–C(10)
C(5)–C(10)–C(11)
C(10)–C(11)–C(12)
Re–C(5)
C(5)–C(10)
C(10)–C(11)
C(11)–C(12)
Ga–Re–Mb
Ga–Re–C(13)
Ga–Re–C(14)
Mb–Re–C(13)
Mb–Re–C(14)
C(13)–Re–C(14)
4. Experimental
4.1. General methods
All reactions were carried out using the standard Schlenck tech-
nique under nitrogen. All solvents were purified and dried by con-
ventional methods, and were distilled under nitrogen prior to use.
Vinylmagnesium bromide and hydrogen chloride in diethyl ether
(Aldrich) were used as received. [Re2(CO)10] and [Cp*Re(CO)3] were
synthesized following literature procedures [24]. The fulvene com-
a
G represents the centroid of the substituted cyclopentadienyl ring.
M represents the midpoint of the C(11)–C(12) olefinic bond.
b
plexes [(g g
6-C5Me4CH2)Re(CO)2(I)] (1a) and [( 6-C5Me4CH2)Re-
(CO)2(C6F5)] (1b) were prepared according to known procedures
[13,14]. Infrared spectra were recorded in solution (CaF2 cell) on
a Perkin–Elmer FT-1605 spectrophotometer. 1H and 13C NMR spec-
tra were recorded on a Bruker AC 400 instrument. All 1H NMR
chemical shifts were referenced using the chemical shifts of resid-
ual solvent resonances. 13C NMR chemical shifts were referenced to
solvent peaks. Mass spectra were recorded on a GCMS-QP5050A
Shimadzu instrument.
piano-stool structure. A 2-propenyl-functionalized tetramethyl-
cyclopentadienyl ligand, linked in a g5 2 chelated bonding mode,
together with two terminal carbonyl ligands, complete the rhe-
:g
nium coordination sphere.
Only a few examples of transition metal compounds with an
alkenyl-substituted C5Me4 ring intramolecularly coordinated in a
g5 g2 bonding mode have been structurally characterized:
:
[(g5
C5Me4CH2CH2CH@CH2)Ru(
analogous rhenium complex [(g5
(CO)2] [11]. Unique structural features of 4 have been sought by
comparison with the related nonchelated [Cp*Re(CO)2(g2
(CH3)2C@CHCOMe)], to our knowledge the only complex of the
type [Cp*Re(CO)2( 2-olefin)] studied by X-ray crystallography [23].
:g
2-C5Me4CH2CH2CH@CH2)Co(Me3SiCCSiMe3)] [22], [(g5
3-C3H5)] [7e] and the closely related
2-C5Me4CH2CH2CH@CH2)Re-
: -
g2
g
4.2. Preparation
:g
4.2.1. [trans-(
g
5-C5Me4CH2CH@CH2)Re(CO)2(I)(H)] (2a)
6-C5Me4CH2)Re(CO)2(I)] (1a) (100 mg,
-
The fulvene complex [(
g
0.199 mmol) was dissolved in THF (15 mL) at 0 °C under nitrogen,
and vinylmagnesium bromide solution 1.0 M/THF 0.3 mL
(0.300 mmol) was added. The reaction mixture was stirred for
5 min, and the IR spectrum showed only two CO absorptions at
g
In terms of the Re–CO (1.905 and 1.913(4) Å) and Re–C(ring
centroid) (1.9327(18) Å) bond distances, the molecular parameters
of
4 -
compare well with those found in [Cp*Re(CO)2(g2
1875 and 1728 cmÀ1, attributed to the anionic species [(g5
-
(CH3)2C@CHCOMe)] and in the 3-butenyl rhenium derivative. The
Re–C(olefin) bond lengths are also comparable, 2.244 and
2.252(4) Å in 4, vs. 2.233 and 2.298(6) Å in the butenyl rhenium
analog, as well as the OC–Re–CO and C(olefin)–Re–C(olefin) bond
angles (85.96(16) and 36.4° vs. 87.4(3) and 36.9°, respectively).
All the bond distances and angles of the propenyl side arm seem
to be normal for C–C single bonds (C(5)–C(10) 1.543(6) and
C(10)–C(11) 1.543(6) Å) and very similar to those observed in the
C5Me4CH2CH@CH2)Re(CO)2(I)]À. Then an HCl solution in diethyl
ether (0.3 mL, 0.300 mmol) was added. The IR spectrum of the
solution showed the complete disappearance of the anionic com-
plex and new CO absorptions at 2021 (s) and 1958 (vs) cmÀ1
.
The solvent was pumped off and hexane (3 Â 10 mL) was added
to the solid residue. The solution was filtered through Celite under
a nitrogen atmosphere and the solvent was concentrated under re-
duced pressure. Complex 2a was isolated as a pale brown solid,
92.6 mg (0.174 mmol) yield: 87.3%. IR (hexane, v(CO) cmÀ1):
2022 (s), 1960 (s). 1H NMR (C6D6) d: À9.12 (Re–H), 1.40 (s, 6H,
C5Me4), 1.42 (s, 6H, C5Me4), 3.02 (m, 2H, CH2ACH), 4.85 (m, 1H,
@CH2), 5.28 (m, 1H, @CH2), 5.69 (m, 1H, CH@).
closely related ruthenium complex [(g5
:g
2-C5Me4CH2CH2CH@
CH2)Ru(
g
3-C3H5)], where also a symmetric Ru–olefin interaction
has been determined (Ru–C(olefin) 2.167 and 2.161 Å).
Remarkably, atom C(10) is clearly out of the least-squares plane
defined by the five carbon atoms of the cyclopentadienyl ring
0.598(5) Å towards the metal center and the bond angle
C(5)AC(10) AC(11) (101.0(3)°) is noticeably smaller than the ideal
tetrahedral angle. These values provide evidence of the strain orig-
inated by the chelate coordination of the cyclopentadienyl-prope-
nyl ligand, and this fact could explain the different reactivity with
CO observed for 4, clearly opposed to that reported for the butenyl
analog, where the bond angle in the carbon atoms of the side arm
exhibit a mean value of 111.9(4)° [11].
4.2.2. [trans-(g
5-C5Me4CH2CH@CH2)Re(CO)2(C6F5)(H)] (2b)
Complex 2b was obtained following the same procedure as for
2a, but using 1b (100 mg, 0.184 mmol). It was isolated as a pale
brown solid, 95.3 mg (0.167 mmol) yield: 90.8%. IR (hexane,
m
(CO) cmÀ1): 2022 (s), 1960 (s). 1H NMR (C6D6) d: À8.95 (Re–H),
1.38 (s, 6H, C5Me4), 1.43 (s, 6H, C5Me4), 2.98 (m, 2H, CH2ACH),
4.77 (m, 1H, @CH2), 5.22 (m, 1H, @CH2), 5.58 (m, 1H, CH@).
4.2.3. [(g
5-C5Me4CH2CH@CH2)Re(CO)3] (3)
3. Conclusion
The hexane solution of 2a, (prepared from 1a, 100 mg,
0.199 mmol), in ca. 10 mL, was bubbled with CO for 3 min and
was heated at 40 °C for 3 h. The IR spectra showed the formation
of two new products. The solution was then chromatographed
through a neutral alumina column. Elution with hexane produced
the complex [Re(CO)5(I)] as a white solid after crystallization from
hexane. Yield: 3.2 mg (0.007 mmol), 3.5%. IR (hexane, v(CO) cmÀ1):
2045(w), 2004(vs). MS (EI, based on 187Re) m/z: 454 [M+], 426
The fulvene complexes [(g
6-C5Me4CH2)Re(R)(CO)2] (R@I, C6F5)
acts as a good precursors for the synthesis of several functionalized
tetramethylcyclopentadienyl rhenium complexes. Reaction with
CH2@CHMgBr followed by HCl yields [trans-(g
5-C5Me4CH2
CH@CH2)Re(R)(H)(CO)2]. Reductive eliminations of HI or C6F5H
afforded propenyl tetramethylcyclopentadienyl derivatives. As

350
F. Godoy et al. / Journal of Organometallic Chemistry 695 (2010) 346–351
[M+ÀCO], 398 [M+À2CO], 370 [M+À3CO]. Elution with hexane pro-
temperature for 15 min. After this time, the solution was
concentrated to ca. 3 mL chromatographed through a short
alumina column. Elution with hexane moved the complex
duced (g
5-C5Me4CH2CH@CH2)Re(CO)3 (3) as a white solid after
crystallization from hexane. Yield: 21 mg (0.260 mmol), 26%. IR
(hexane,
m
(CO) cmÀ1): 2014 (s), 1924 (s). 1H NMR (CDCl3) d: 2.15
[(
g
5-C5Me4CH2CH@CH2)Re(CO)2(PMe3)]
(5),
(44 mg,
(s, 6H, C5Me4), 2.17 (s, 6H, C5Me4), 3.17 (td, JHH = 5,9; 1,6 Hz, 2H,
CH2–CH), 4.95 (qd, 1H, JHH = 17,2; 1,6 Hz, @CH2), 5.02 (qd, 1H, JHH
10,3; 1,6 Hz, @CH2), 5.74 (m, 1H, CH@). 13C{1H} RMN (CDCl3) d:
10.8 (s, C5Me4), 12.0 (s, C5Me4), 30.2 (s, CH2), 98.9 (s, C5Me4), 99.2
(s, Cipso, C5Me4), 100.0 (s, C5Me4), 116.0 (s, CH@CH2), 137.0 (s,
CH@CH2), 198.2 (s, CO). MS (EI, based on 187Re) m/z: 432 [M+],
404 [M+ÀCO], 391 [M+ÀCH2CH@CH2], 374 [M+À2COÀ2H]. Anal.
Calc. for C15H17O3Re: C, 41.75; H, 3.97. Found: C, 42.06; H, 4.08%.
0.092 mmol, yield: 46%). Successive elution with hexane
afforded the complex 4, which was obtained as pure sample
8 mg (0.019 mmol), yield: 10%.
4.3. X-ray structural determination of 4
Suitable yellow crystals for X-ray diffraction experiment were
obtained by slow diffusion of hexane into concentrated dichloro-
methane solution of 4. Intensity data were collected at low temper-
4.2.4. [(g5 2-C5Me4CH2CH@CH2)Re(CO)2] (4)
:g
A solution of pentafluorophenyl hydride (2b) (prepared from
1b, 100 mg, 0.184 mmol) in hexane (10 mL), was heated under
CO at 45 °C for 6 h. An IR spectrum recorded at this time showed
three new complexes. The reaction mixture was concentrated un-
der reduced pressure to ca. 3 mL. and then was chromatographed
through an alumina column. The hexane elutions afforded [Re-
ature (100(2) K) on
diffractometer equipped with graphite-monochromated Mo K
radiation (k = 0.71073 Å) using narrow frames (0.3° in ). Cell
a Bruker SMART CCD area detector
a
x
parameters were refined from the observed setting angles and
detector positions of strong reflections (4806 refl., 2h < 56.56°).
Data were corrected for Lorentz and polarization effects, and mul-
ti-scan absorption corrections were applied with SADABS program
[25]. The structures were solved by Patterson method and com-
pleted by successive difference Fourier syntheses [25]. Refinement,
by full-matrix least-squares on F2 with SHELXL97 [26], was carried
out including isotropic and subsequent anisotropic displacement
parameters for all non-hydrogen atoms. Hydrogens for the methyl
groups were included at calculated positions and refined with posi-
tional and thermal riding parameters; those of the allylic lateral
chain were included from observed positions and freely refined
as isotropic atoms. The highest electronic residuals (around 1.0 e/
Å3) were observed in close proximity of the Re metal and have
no chemical sense. Atomic scattering factors, corrected for anoma-
lous dispersion, were used as implemented in the refinement pro-
gram [26].
(CO)5(C6F5)]. The second fraction produced [(
CH2)Re(CO)3] (3), while successive elution with hexane yielded
[(g5 2-C5Me4CH2CH@CH2)Re(CO)2] (4) as a white solid after crys-
g
5-C5Me4CH2CH@
:g
tallization from hexane. [Re(CO)5(C6F5)] was obtained as a white
solid after pumped off the solvent, 2.4 mg (0.005 mmol) yield:
2.6%. IR (hexane, m
(CO) cmÀ1): 2039(w), 2004(vs). MS (EI, based
on 187Re) m/z: 494 [M+], 466 [M+ÀCO], 438 [M+À2CO], 410
[M+À3CO]. Complex 3 was isolated as a white solid 21.0 mg
(0.049 mmol) yield 26%. Complex 4 was obtained as pure sample
with successive elution with hexane, 32 mg (0.079 mmol), yield:
43%. IR (hexane, m
(CO), cmÀ1): 1962 (s), 1891 (s). 1H MNR (CDCl3)
d: 1.39 (dd, 1H, JHH = 2.9, 9.8 Hz, CH2CH), 1.59 (s, 3H, C5Me4), 2.16
(s, 3H, C5Me4), 2.18 (m, 1H, CH2), 2.34 (s, 6H, C5Me4), 2.39 (m,
1H, CH), 2.41 (s, 6H, C5Me4), 2.68 (dd, 1H, JHH = 2.9, 7.0 Hz,
@CH2), 3.20 (ddd, 1H, JHH = 1.0, 7.0, 13.7 Hz, @CH2). 13C1H NMR
(CDCl3) d: 9.3 (s, C5Me4), 11.5 (broad, C5Me4), 12.6 (s, C5Me4),
22.0 (s, CH2), 31.3 (s, CH2), 58.3 (s, CH), 93.6 (s, C5Me4), 95.0 (s,
C5Me4), 96.01 (s, C5Me4), 99.7 (s, C5Me4), 116.0 (s, Cipso–C5Me4),
207.5 (s, CO), 207.7 (s, CO). MS (EI, based on 187Re) m/z: 404 M+,
374 M+ÀCOÀ2H, 346 M+-2CO-2H. Anal. Calc. for C14H17O2Re: C,
41.67; H, 4.25. Found: C, 41.98; H, 4.12%.
Crystal data for compound 4: C14H17O2Re, M = 403.48; yellow
cubic block, 0.163 Â 0.141 Â 0.095 mm3; monoclinic, P21/n;
a = 8.5254(9), b = 12.9818(14), c = 11.6783(13) Å, b = 93.649(2)°,
Z = 4; V = 1289.9(2) Å3; Dc = 2.078 g/cm3;
l
= 9.408 mmÀ1, mini-
mum and maximum transmission factors 0.262 and 0.424;
2hmax = 56.56°; 8404 reflections collected, 3045 unique
[Rint = 0.0280]; number of data/restrains/parameters 3045/0/178;
final GOF 1.046, R1 = 0.0238 [2799 reflections, I > 2
wR2 = 0.0552 for all data.
r(I)],
4.2.5. [(g
5-C5Me4CH2CH@CH2)Re(CO)2(PMe3)] (5)
(a) To an hexane solution of 2a (prepared from 1a, 100 mg,
0.199 mmol), in ca. 10 mL, PMe3 was added (0.2 mL, 1.0 M
THF solution) and the reaction mixture was stirred for
5 min at room temperature. After this time, the IR spectra
showed two absorption bands at 1924 and 1860 cmÀ1. The
solution was concentrated to ca. 3 mL chromatographed
through a short alumina column. Elution with hexane
Acknowledgements
The financial support of FONDECYT Chile under project
11060524 and of MEC under CONSOLIDER-INGENIO-2010 program
(CSD 2006-0015) is acknowledged. The loan of NH4ReO4 from
MOLYMET-Chile is also much appreciated.
moved the complex [(
g
5-C5Me4CH2CH@CH2)Re(CO)2-
(CO),
Appendix A. Supplementary material
(PMe3)] (5), (68 mg, 0.138 mmol, 69%). IR (hexane,
m
cmÀ1): 1924 (s), 1860 (s). 1H MNR (CDCl3) d: 1.59 (d,
J = 9.0, 9H, PMe3), 2.09 (s, 12H, C5Me4), 3.27 (td, JHH = 6.0,
1,5 Hz, 2H, CH2–CH), 4.96 (qd, 1H, JHH = 17,0; 1,5 Hz,
@CH2), 5.01 (qd, 1H, JHH 10,1; 1,5 Hz, @CH2), 5.79 (m, 1H,
CH@). 13C{1H} NMR (CDCl3) d: 11.4 (s, broad, C5Me4),
22.7 (d, J = 34.8 Hz, PMe3), 30.8 (s, CH2), 98.8 (s, C5Me4),
99.4 (s, Cipso, C5Me4), 100.4 (s, C5Me4), 116.1 (s, CH@CH2),
136.8 (s, CH@CH2), 206.2 (d, J = 7.6 Hz, CO). 31P NMR (CDCl3)
CCDC 748385 contains the supplementary crystallographic data
for 4. These data can be obtained free of charge from The Cam-
bridge Crystallographic Data Centre via www.ccdc.cam.ac.uk/da-
ta_request/cif. Supplementary data associated with this article
can be found, in the online version, at doi:10.1016/
j.jorganchem.2009.10.042.
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